SUBORDER A 



ZALAMBDODONTA 



39 



are secodont, the upper ones mostly tritubercular, seldom quadritubercular, 

 their tubercles separate or connected by ridges. The lower M consist of a 

 three-pointed trigonid and of a low, often very small two-rooted talonid. The 

 change of teeth often occurs in the embryonic stage, whereas in one genus 

 the milk teeth are retained for a long time. The Insedivora may be 

 divided into two groups : the Menotyphla, in which the pelvic symphysis 

 is formed by both pubes and ischia, and the Lipotyphla, among which a 

 symphysis is either lacking or is formed only by the pubes. To the Menotyphla 

 belong the Tupaiidae, recent in eastern Asia, and the African Macroscelididae. 

 Of these fossil forms are not certainly known. 



The Lipotyphla are divided into Zalambdodonta and Dilambdodonta, to 

 which are now attributed several extinct families, which show affinities 

 with primates, creodonts and rodents. 



Suborder A. ZALAMBDODONTA Gill. 



Upper M mostly pseudo-tritubermlar. Lower with strong trigonid and very 

 much reduced talonid. Symphysis pubis reduced or wanting. 



Family 1. Ohrysochloridae. 



This family, now native in South Africa and specialised like the moles, 

 but having hypsodont P and M, is supposed to have one representative, 

 namely, Xenotherium Douglass, in the Oligocene (White Eiver beds) of North 

 America. 



Family 2. Necrolestidae Scott.i 



Necrolestes Ameghino (Fig. 60). 



4.1.3.3. 



/ small, C normally developed, 



4.1.3.3. 



P^ two-rooted in both jaws, the lower with protocone and paracone, the rest 

 hypsodont and tritubercular like M. In respect to skull, dentition and 

 specialisation of the extremities very like the South African Ohrysochloridae, 

 but with longer snout. Upper Miocene 



of Santa Cruz, Patagonia. 



^p4, TT^l mSjna 



Fig. 60. 



Necrolestes patayonicus Ameghino. a, skull ; &, 

 humerus, l/i- Upper Miocene of Santa Cruz, 

 Patagonia. (After Scott.) 



Fig. 61. 



Micropternod'iis horealis Matthew. Lower White 

 River beds of Oligocene ; Montana. Exterior and 

 interior aspect of mandible. 2/1. (After Matthew.) 



Family 3. Oentetidae. 



This family is now restricted to Madagascar, with the exception of a 

 recent genus Solenodon of Cuba, and closely related to the West African 

 Potamogalidae. Oligocene (White River beds) ; Montana. 



^ Eept. Princeton University E.xped. to Patagonia, vol. v. part ii., 1905. 



